Further work on motions in DNA and synthetic polynucleotides will be performed. Hydrogen exchange studies using both the tritium-sephadex method and the stopped-flow H-D exchange method will be used to study opening reactions in DNA-histone complexes, ribosomes, circular DNA, and some synthetic polynucleotide double helices. Also the relationships connecting DNA opening reactions and the binding of various dye molecules and other intercalators will be studied. Work on the kinetics and equilibrium of HbS gelation will be pursued. We want to determine the correlations between severity of the disease and influences affecting the physical-chemical parameters of gelation. Our previous work on the role of concentration-dependent protein activity and the presence of chemical inhibitors and non-HbS proteins will be extended to the effects of oxygen, pH, etc., and the pertinence of all these for events at red cell concentrations will be investigated.